I am working a zx250 here and had a couple shorted outputs I found not letting it start up .
Replaced those and now left channel seems ok but right channel is heating up really quickly 10 or so seconds and it must be turned off holding fingers on outputs judging heat. other channel cold still.whats causing this?
the left channel had 25mv and the right had 35mv dc offset.
I replaced both left and right channels from the old 2sd1975 and 12b1317 with 2sc5200 and 2sa1943.
. Id like to know how to test this amp as well .i tried using ground as my neg test lead and cant seem to see any rail voltages.
Replaced those and now left channel seems ok but right channel is heating up really quickly 10 or so seconds and it must be turned off holding fingers on outputs judging heat. other channel cold still.whats causing this?
the left channel had 25mv and the right had 35mv dc offset.
I replaced both left and right channels from the old 2sd1975 and 12b1317 with 2sc5200 and 2sa1943.
. Id like to know how to test this amp as well .i tried using ground as my neg test lead and cant seem to see any rail voltages.
Look for blown open fuse resistors. A failure mode like described had to cause fuse resistor failures also They will be either green or grey bodied 1/4 watt fuses and they are located all the way back just pass input diff pair to the outputs..
This amp has red leds as I recall all four, two per channel should be lite up and equal brightness, if not replace them as needed and check fuse resistors near by....
Cold channel probably has open resistors, Hot channel may have bias set incorrectly.
Both channels should have less then 10 MVDC offset on the speaker terminals if you have replaced all defective components . Your DC output level are way too high check Diff input pairs for damage and replace as need be..
This amp has red leds as I recall all four, two per channel should be lite up and equal brightness, if not replace them as needed and check fuse resistors near by....
Cold channel probably has open resistors, Hot channel may have bias set incorrectly.
Both channels should have less then 10 MVDC offset on the speaker terminals if you have replaced all defective components . Your DC output level are way too high check Diff input pairs for damage and replace as need be..
ok I have it running for a while now it needed a 100 ohm fuse resistor and it came out of it . just put a regular 1/4 watt in it .. I notice this v2 doesnt seem to have any led on the boards. looks like one channel the one i fixed it is around 15mv and i cant get the other one below 40mv what else could i check to get them in spec?.. The amp seems to have good output on both channels and no distortion on the scope is it just a old component issue?
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I see there on the input boards there is a bunch of them and they look hard to get too. do i have to remove them to test them ? and are they like outputs where you have a complement pair as well ? npn pnp type thing.. I am selling this amp so i just wanted to make it work well enough for sale so i might leave it it seems to be stable just not perfect on the offset . but if i get one I am going to keep i will go through the input boards and fix these little boogers.
Also I sold my Ppi a1200.2 you helped me with a while back to a ebayer and he said it did not work and sent me the amplifier back with a switched board that is in pretty bad condition....ughhhh I want to try to get working so hopefully you can help me sort this mess out when i get to it . ill have to show you a picture of it. i was very upset that i sent a perfect working amplifier to him and he sent back a piece of junk. it just pulls a ton of current and the protect light is on. so i will have to go through it.
Again I really appreciate your time on this
Also I sold my Ppi a1200.2 you helped me with a while back to a ebayer and he said it did not work and sent me the amplifier back with a switched board that is in pretty bad condition....ughhhh I want to try to get working so hopefully you can help me sort this mess out when i get to it . ill have to show you a picture of it. i was very upset that i sent a perfect working amplifier to him and he sent back a piece of junk. it just pulls a ton of current and the protect light is on. so i will have to go through it.
Again I really appreciate your time on this
Two things on ebay sales...
When selling an amp, include a high quality photo of the board and make a note that if the board is tampered with, you will contest any returns.
Use tamper evident labels over the cover screws and say that on returns will be accepted if the stickers show evidence of tampering.
This isn't foolproof but may discourage some that want to try to scam you.
When selling an amp, include a high quality photo of the board and make a note that if the board is tampered with, you will contest any returns.
Use tamper evident labels over the cover screws and say that on returns will be accepted if the stickers show evidence of tampering.
This isn't foolproof but may discourage some that want to try to scam you.
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